1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
/*
* DivX (XSUB) subtitle encoder
* Copyright (c) 2005 DivX, Inc.
* Copyright (c) 2009 Bjorn Axelsson
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avcodec.h"
#include "bytestream.h"
#include "put_bits.h"
/**
* Number of pixels to pad left and right.
*
* The official encoder pads the subtitles with two pixels on either side,
* but until we find out why, we won't do it (we will pad to have width
* divisible by 2 though).
*/
#define PADDING 0
#define PADDING_COLOR 0
/**
* Encode a single color run. At most 16 bits will be used.
* @param len length of the run, values > 255 mean "until end of line", may not be < 0.
* @param color color to encode, only the lowest two bits are used and all others must be 0.
*/
static void put_xsub_rle(PutBitContext *pb, int len, int color)
{
if (len <= 255)
put_bits(pb, 2 + ((ff_log2_tab[len] >> 1) << 2), len);
else
put_bits(pb, 14, 0);
put_bits(pb, 2, color);
}
/**
* Encode a 4-color bitmap with XSUB rle.
*
* The encoded bitmap may be wider than the source bitmap due to padding.
*/
static int xsub_encode_rle(PutBitContext *pb, const uint8_t *bitmap,
int linesize, int w, int h)
{
int x0, x1, y, len, color = PADDING_COLOR;
for (y = 0; y < h; y++) {
x0 = 0;
while (x0 < w) {
// Make sure we have enough room for at least one run and padding
if (pb->size_in_bits - put_bits_count(pb) < 7*8)
return -1;
x1 = x0;
color = bitmap[x1++] & 3;
while (x1 < w && (bitmap[x1] & 3) == color)
x1++;
len = x1 - x0;
if (PADDING && x0 == 0) {
if (color == PADDING_COLOR) {
len += PADDING;
x0 -= PADDING;
} else
put_xsub_rle(pb, PADDING, PADDING_COLOR);
}
// Run can't be longer than 255, unless it is the rest of a row
if (x1 == w && color == PADDING_COLOR) {
len += PADDING + (w&1);
} else
len = FFMIN(len, 255);
put_xsub_rle(pb, len, color);
x0 += len;
}
if (color != PADDING_COLOR && (PADDING + (w&1)))
put_xsub_rle(pb, PADDING + (w&1), PADDING_COLOR);
avpriv_align_put_bits(pb);
bitmap += linesize;
}
return 0;
}
static int make_tc(uint64_t ms, int *tc)
{
static const int tc_divs[3] = { 1000, 60, 60 };
int i;
for (i=0; i<3; i++) {
tc[i] = ms % tc_divs[i];
ms /= tc_divs[i];
}
tc[3] = ms;
return ms > 99;
}
static int xsub_encode(AVCodecContext *avctx, unsigned char *buf,
int bufsize, const AVSubtitle *h)
{
uint64_t startTime = h->pts / 1000; // FIXME: need better solution...
uint64_t endTime = startTime + h->end_display_time - h->start_display_time;
int start_tc[4], end_tc[4];
uint8_t *hdr = buf + 27; // Point behind the timestamp
uint8_t *rlelenptr;
uint16_t width, height;
int i;
PutBitContext pb;
if (bufsize < 27 + 7*2 + 4*3) {
av_log(avctx, AV_LOG_ERROR, "Buffer too small for XSUB header.\n");
return -1;
}
// TODO: support multiple rects
if (h->num_rects != 1)
av_log(avctx, AV_LOG_WARNING, "Only single rects supported (%d in subtitle.)\n", h->num_rects);
// TODO: render text-based subtitles into bitmaps
if (!h->rects[0]->pict.data[0] || !h->rects[0]->pict.data[1]) {
av_log(avctx, AV_LOG_WARNING, "No subtitle bitmap available.\n");
return -1;
}
// TODO: color reduction, similar to dvdsub encoder
if (h->rects[0]->nb_colors > 4)
av_log(avctx, AV_LOG_WARNING, "No more than 4 subtitle colors supported (%d found.)\n", h->rects[0]->nb_colors);
// TODO: Palette swapping if color zero is not transparent
if (((uint32_t *)h->rects[0]->pict.data[1])[0] & 0xff000000)
av_log(avctx, AV_LOG_WARNING, "Color index 0 is not transparent. Transparency will be messed up.\n");
if (make_tc(startTime, start_tc) || make_tc(endTime, end_tc)) {
av_log(avctx, AV_LOG_WARNING, "Time code >= 100 hours.\n");
return -1;
}
snprintf(buf, 28,
"[%02d:%02d:%02d.%03d-%02d:%02d:%02d.%03d]",
start_tc[3], start_tc[2], start_tc[1], start_tc[0],
end_tc[3], end_tc[2], end_tc[1], end_tc[0]);
// Width and height must probably be multiples of 2.
// 2 pixels required on either side of subtitle.
// Possibly due to limitations of hardware renderers.
// TODO: check if the bitmap is already padded
width = FFALIGN(h->rects[0]->w, 2) + PADDING * 2;
height = FFALIGN(h->rects[0]->h, 2);
bytestream_put_le16(&hdr, width);
bytestream_put_le16(&hdr, height);
bytestream_put_le16(&hdr, h->rects[0]->x);
bytestream_put_le16(&hdr, h->rects[0]->y);
bytestream_put_le16(&hdr, h->rects[0]->x + width -1);
bytestream_put_le16(&hdr, h->rects[0]->y + height -1);
rlelenptr = hdr; // Will store length of first field here later.
hdr+=2;
// Palette
for (i=0; i<4; i++)
bytestream_put_be24(&hdr, ((uint32_t *)h->rects[0]->pict.data[1])[i]);
// Bitmap
// RLE buffer. Reserve 2 bytes for possible padding after the last row.
init_put_bits(&pb, hdr, bufsize - (hdr - buf) - 2);
if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0],
h->rects[0]->pict.linesize[0]*2,
h->rects[0]->w, (h->rects[0]->h + 1) >> 1))
return -1;
bytestream_put_le16(&rlelenptr, put_bits_count(&pb) >> 3); // Length of first field
if (xsub_encode_rle(&pb, h->rects[0]->pict.data[0] + h->rects[0]->pict.linesize[0],
h->rects[0]->pict.linesize[0]*2,
h->rects[0]->w, h->rects[0]->h >> 1))
return -1;
// Enforce total height to be a multiple of 2
if (h->rects[0]->h & 1) {
put_xsub_rle(&pb, h->rects[0]->w, PADDING_COLOR);
avpriv_align_put_bits(&pb);
}
flush_put_bits(&pb);
return hdr - buf + put_bits_count(&pb)/8;
}
static av_cold int xsub_encoder_init(AVCodecContext *avctx)
{
if (!avctx->codec_tag)
avctx->codec_tag = MKTAG('D','X','S','B');
avctx->bits_per_coded_sample = 4;
return 0;
}
AVCodec ff_xsub_encoder = {
.name = "xsub",
.long_name = NULL_IF_CONFIG_SMALL("DivX subtitles (XSUB)"),
.type = AVMEDIA_TYPE_SUBTITLE,
.id = AV_CODEC_ID_XSUB,
.init = xsub_encoder_init,
.encode_sub = xsub_encode,
};
|
